This invention pertains to hermetic rotary compressors for compressing refrigerant in refrigeration systems such as air conditioners, refrigerators, and the like. In particular, the invention relates to providing lubrication oil to bearing surfaces of the rotary compressor.
In general, prior art horizontal hermetic rotary compressors comprise a housing which is hermetically sealed. Located within the housing are an electric motor and a compressor mechanism. The electric motor is connected to a horizontal crankshaft which has an eccentric portion thereon. The eccentric portion of the crankshaft is located within a bore of the compressor cylinder. A roller located within the bore is mounted on the eccentric portion of the crankshaft and is driven thereby. The roller cooperates with a sliding vane to compress refrigerant within the bore of the cylinder.
Rotary hermetic compressors of the type herein disclosed generally have a pressurized or high side sealed housing. The compressor is connected into a refrigeration circuit by means of suction and discharge tubes. In prior art compressors, the motor stator has been secured to the interior wall of the housing by shrink fitting and the compressor cylinder is generally welded to the housing. A motor rotor is journalled in a bearing and drives the crankshaft. The suction tube extends through the housing and is sealingly connected thereto. The end of the suction tube which extends into the housing is connected to the cylinder and conducts low pressure refrigerant directly to the cylinder bore for compression therein. The connection of the suction tube to the cylinder is usually made by press fitting the tube into an aperture in the cylinder wall.
It is necessary to supply lubricating oil to the rotating and sliding parts between the rotor shaft and its bearings. It has been a conventional practice to forcibly supply lubricating oil to the parts requiring lubrication by pumping oil up from an oil sump at the bottom of the sealed housing by means of an oil supply pump.
A prior art compressor, as shown in U.S. Pat. No. 4,472,121, teaches how lubricating oil is pumped through a central lubrication bore from a lubricant feed tube which is opened at one end within a lubricant oil pool. The feed tube is intermittently subjected to refrigerant gas discharged from the compression unit. This type of compressor includes excess parts as compared to the invention described herein.
Another prior art horizontal compressor, U.S. Pat. No. 4,781,542, discloses a divider that separates the motor and compressor unit portions of the compressor while discharge pressure is communicated through the crankshaft into the motor cavity to lower the oil sump level in the motor chamber. The discharge gases are then passed through the divider to the compressor unit portion permitting a higher oil sump level due to a pressure differential across the partition. In this type of prior art compressor, it is impossible to achieve direct oil lubrication of the outer bearing and other rotating parts from the oil sump because of a cover separating the outboard bearing and discharge compressor port.